XRISM Finds the Changing-look Active Galactic Nucleus NGC 1365 in an Extended Low State: A Dense, Highly Ionized Outflow Obscures the Central Source

Journal Article · Mon Jan 19 00:00:00 EST 2026 · The Astrophysical Journal. Letters

DOI:https://doi.org/10.3847/2041-8213/ae307d· OSTI ID:3014617

Zaidouni, Fatima ^[1]; Kara, Erin ^[1]; Kosec, Peter ^[2]; Behar, Ehud ^[3]; Mushotzky, Richard ^[4]; Koss, Michael ^[5]; Juráňová, A. ^[1]; Kammoun, Elias ^[6]; Brenneman, Laura W. ^[2]; Chakraborty, Joheen ^[1]; Ebisawa, Ken ^[7]; Eckart, Megan E. ^[8]; Fabian, Andrew C. ^[9]; Fukazawa, Yasushi ^[10]; García, Javier A. ^[11]; Gu, Liyi ^[12]; Masterson, Megan ^[1]; Ogawa, Shoji ^[7]; Okajima, Takashi ^[13]; Paltani, Stéphane ^[14] ; Rogantini, Daniele ^[15]; Terashima, Yuichi ^[16]; Williams, Brian J. ^[13]; Yamada, Satoshi ^[17]

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1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
2. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)
3. Technion-Israel Institute of Technology, Haifa (Israel)
4. Univ. of Maryland, College Park, MD (United States)
5. Eureka Scientific, Inc., Oakland, CA (United States)
6. California Institute of Technology (CalTech), Pasadena, CA (United States)
7. Japan Aerospace Exploration Agency (ISAS/JAXA), Sagamihara, Kanagawa (Japan). Institute of Space and Astronautical Science
8. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
9. Univ. of Cambridge (United Kingdom)
10. Hiroshima Univ. (Japan)
11. California Institute of Technology (CalTech), Pasadena, CA (United States); NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
12. SRON Space Research Organization Netherlands, Leiden (Netherlands)
13. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
14. Univ. of Geneva, Versoix (Switzerland)
15. Univ. of Chicago, IL (United States)
16. Ehime Univ., Matsuyama (Japan)
17. Tohoku Univ., Sendai (Japan)

We present the first XRISM/Resolve observations of the active galactic nucleus NGC 1365, obtained in 2024 February and July. NGC 1365 is known for rapid transitions between Compton-thick and Compton-thin states, along with strong absorption from a highly ionized wind. During our observations, the source was found in a persistent low-flux state, characterized by a decrease in hard-X-ray luminosity and significant line-of-sight obscuration. In this state, XRISM/Resolve reveals clear Fe XXV and Fe XXVI absorption lines together with, for the first time in this source, corresponding emission lines. These features may arise either from reemission from a photoionized wind (P Cygni profile) or from collisionally ionized gas associated with outflow-driven shocks in the interstellar medium. We estimate the wind launch radius to be approximately 10¹⁶ cm (∼10⁴R_g), consistent with the location of the X-ray broadline region. We also resolve a broadened Fe Kα line by σ ∼ 1300 km s⁻¹, placing it at similar scales to the wind, consistent with radii inferred from disk-broadening models and the variability of the Fe Kα broad line. The similarity of the Fe Kα profile to the Hβ wing and broad Paα width indicates that the X-ray-emitting region is likely cospatial with the optical/infrared broadline region and originates from the same gas.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: National Aeronautics and Space Administration (NASA); USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 3014617
• Report Number(s): LLNL--JRNL-2014842
• Journal Information: The Astrophysical Journal. Letters, Journal Name: The Astrophysical Journal. Letters Journal Issue: 1 Vol. 997; ISSN 2041-8205; ISSN 2041-8213
• Publisher: IOP Publishing
• Country of Publication: United States
• Language: English

Related Subjects

Astronomy and AstroPhysics